Straightening machine



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STRAIGHTENING MACHINE Filed May 19, 1967 18 Sheets-Sheet 15 Oct. 28, 1969 Filed llay 19, 1967 D. L. JUDGE ET AL STRAIGHTENING MACHINE 18 Sheets-Sheet 1'7 ATTORNEYS United States Patent 3,474,650 STRAIGHTENING MACHINE Donald L. Judge, Lansing, and James R. Clewley, Grand Ledge, Mich., assignors to Industrial Metal Products Corporation, a corporation of Michigan Filed May 19, 1967, Ser. No. 639,832 Int. Cl. B21b 37/00; B21j 7/26 U.S. Cl. 72-12 18 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION The present invention relates to means and methods for automatically detecting axial distortion in a part and making the necessary correction within prescribed tolerances at reasonably high production rates.

Axial distortions are commonly introduced into rotational parts that are green ground to include bearing surfaces, gear faces, and the like when they are subsequently heat treated. This is particularly true with axle shafts of any length and gear head members including a shaft part of smaller dimension where there are variations in material cooling rates.

In most rotational parts, axial distortion is commonly found by rotating the part, noting any eccentricity, and making the necessary correction either while the part is rotating or afterwards. With certain parts, if correction is attempted while the part is rotating, overstressing may result in brittle or broken work pieces. If correction is made with the part stationary, normally under manual control, time is lost in locating the distortion, determining the amount of correction required, and in manually regulating the amount of bending of the work piece to that required to make it straight.

SUMMARY OF THE INVENTION This invention is directed to a means and method for detecting the presence and radial plane of axial distortion in a rotational part, and for correcting the part automatically and immediately thereafter without moving the part to another location and without requiring that the amount of distortion be predetermined.

The present invention makes use of a comparative detection system which includes three circumferentially spaced differential probes to determine the presence and relative location of the plane of distortion.

The rotational part is straightened by deflecting it in the plane of the distortion through the true rotational axis a predetermined amount as necessary for it to spring back to a true straight position, as gauged by the differential probes. To accommodate the relative differences in metallurgical structure and circumferential size, which affect the recovery of parts within their elastic limits, a series of deflections of increasing incremental amounts is automatically provided to assure the straightening of all parts after one or more of the programmed deflections.

In the particular machine hereinafter disclosed for practicing this invention, a transfer line delivers parts sequentially to a straightening station of the machine where each is picked up, centered and examined to determine both the presence and relative location of any axial distortion beyond prescribed tolerances. If correction is needed, it is automatically repositioned, rotationally, relative to an overhead ram used in the straightening process. By use of the three probes mentioned, the ,part is turned through the shortest distance to dispose the plane of distortion vertically and crowned upwardly. When the ram is actuated, the part is set down on rocker supports to permit deflection beyond the true rotational axis. The part is inspected after each deflection and if it is not within tolerances the ram is signalled to deflect the part agains, once, twice or more times as necessary to straighten it. Although provision may be made for a progressive series of twenty or more deflections, usually four or five is sufficient since the metallurgical composition of the part and its relative size are the determining factors rather than the extent of initial distortion.

DESCRIPTION OF THE DRAWINGS The numerous objects and advantages to be gained in the practice of this invention will best be understood and appreciated from the detailed description of a preferred embodiment as shown by the accompanying drawings wherein:

FIG. 1 is a front elevation of a differential drive pinion straightening machine embodying the various features of the present invention.

FIG. 2 is a top plan view of the machine.

FIG. 3 is a side elevation of the machine.

FIG. 4 is an enlarged partially sectioned front elevational view of one of the work positioning devices shown in FIG. 1.

FIG. 5 is an enlarged partially sectioned side elevational view of the straightening ram and upper inspection probes.

FIG. 6 is an enlarged top plan view of the work bed with a work part shown in phantom outline as received thereover.

FIG. 7 is an enlarged cross-sectional view of the work bed of the previous drawing figure, as seen in the plane of line 77, and showing the lower inspection probe in greater detail.

FIG. 8 is an enlarged cross-sectional view, showing certain details of the positioning device of FIG. 4 as seen in the plane of line 88 thereon.

FIG. 9 is an enlarged cross-sectional view of one of the upper probes as seen in the plane of line 9-9 in FIG. 5.

FIG. 10 is an enlarged front elevational view of the straightening ram mechanism, with the lower bed and upper inspection probes omitted.

FIG. 11 is a fragmentary top plan view of the straightening ram mechanism of the last mentioned drawing figure and shows the ram cylinder centrally thereof in dotted outline.

FIG. 12 is a cross-sectional view taken in the plane of line 1212 of the last mentioned drawing figure and shows the ram cylinder in greater detail.

FIG. 13 is a fragmentary front elevational view of the anvils which receive and support the work piece for straightening and shows the end of the straightening ram as disposed thereover.

FIG. 14 is a cross-sectional view of one of the anvil members as seen in the plane of line 14-14 of FIG. 13.

FIG. 15 is an enlarged side elevational view of the shoulder probe of the straightening machine, as positioned relative to the back face of a work part shown in phantom outline.

FIG. 16, on the preceding sheet of drawings, is a top plan view of the shoulder probe as seen in the plane of line 16-16 in FIG. 10.

FIG. 17 is a schematic presentation of the hydraulic system of the straightening machine.

FIG. 18 is a schematic presentation of the amplifier circuit of the disclosed straightening machine.

FIGS. 19-24 are consecutively related schematic illus trations of the electrical system.

DETAILED DESCRIPTION The machine shown 'by the drawings and hereinafter described is for inspecting and straightening automotive differential drive pinions having integral shafts subjected to axial distortion both in the shaft and relative to the gear head as a consequence of heat treating in the course of normal production to harden Work surfaces.

The machine includes a base 10 on which is provided work transfer means 12 for receiving individual work parts 14 and moving them sequentially towards a position Where they are inspected and straightened when necessary.

The transfer means 12 is of the walking beam type and is best shown in FIGS. 2 and 3. It includes a pair of stationary side rails 16 with a pair of walking beam members 18 disposed in close parallel spaced relation thereto and operated by power cylinders 20 connected to hell crank and lever arms 24 and 26 which are engaged to the beam members and move them up, forward, down and back in the conventionally known manner to move a series of work parts forward together.

Head and tail stock engaging devices 28 and 30, shown in FIG. 1 are mounted on the base 10 and are aligned on opposite sides of the transfer means 12 for axial engagement with work parts received therebetWeen. They are similar in construction and operation and will be described with respect to the tail stock engaging device shown in FIG. 4.

The head and tail stock engaging devices each include housing parts 32 and 34 which are secured together and have an arbor or spindle 36 that extends through both of them. The housing parts are mounted on or formed to include supports 38 and 40 to position the spindle at the height of the work parts on the transfer rails 16 and each spindle includes a center-point fitting 42 for centering en- .gagement in the live centers in the ends of work parts to be received therebetween.

The housing part 32 includes a sleeve member 44 that carries the spindle and is reciprocal within a bore 46 as limited by a fixed stop 48 received in a guide slot 50 inthe sleeve. The spindle is mounted in spaced concentric relation within the sleeve member and includes a ball and socket arrangement 52 at its outermost end permitting limited relative movement in the sleeve and axial rotation.

Rotational drive is imparted to the spindle 36 by a drive motor 54, mounted on a housing 56 secured to the end of the sleeve member 44, and through a flexible drive coupling 58 provided in the housing.

A power cylinder 60 is mounted on the housing 56 and has the piston rod part engaged to the support 38 to reciprocate the sleeve member and its spindle fore and aft.

The housing part 34 through which the spindle 36 extends is formed to provide centering support for the spindle at spaced locations as best shown by FIG. 8. The centering supports are provided in a common radial plane at each end of the housing 34 and include centering pins 62 which intersect the bore passage 64 through which the spindle passes. They are radially disposed and are backed by compression springs 66 in spring cups 68, and are strong enough to carry the weight of the spindle when engaged with a work part but will allow for rotation of the spindle and will yield to straightening forces imposed on the work part, as later described.

To assure more precise centering of the spindle, clamping pins 70 are provided between the centering pins, in the same radial plane, and are activated by hydraulic fluid pressure. The pressure fittings 72 for the clamping pins are interconnected to assure equal pressure and each is provided with a chamber area 74 of like size and a stop collar 75 to limit travel. The pins designated as 76 are pressed into fittings 72 and act like a key to keep clamping pins 70 from rotating. As later described, the clamping pins serve to positively locate the spindles 36 for establishing a reference axis when the work parts are being inspected for axial distortion.

The work parts are inspected for axial distortion While supported on the spindles 36 by the two upper probing members 78 and 80 which are alike and are best shown by FIG. 5, and a third lower probing member 122 best shown in FIG 7.

The two upper probing members are mounted on supports 82 and 84 projecting out from the front and back sides of the ram housing 86 directly over the work part and are directed down and in under the housing for engagement with the work parts from relatively opposite sides. They are mounted on the ends of piston rods 88 of power cylinders 90, provided on the supports, and are guided for reciprocal movement on a radial line relative to the axis of the work part by guide rods 92 received in guide holes 94- in the supports. Each probing member is provided with an adjustable stop 96 for engagement with a shoulder stop 98 on the ram housing to limit forward travel to a predetermined extent that assures contact with the Work piece and a cushion stop 100 is provided for the piston rod connection so that the stroke imposed by the power cylinder will not adversely aifect the terminal positioning.

An extension 102 on the forward end of the probing member accommodates and guides the actual probe 104 which is biased outwardly by a spring 106 and collar arrangement 108. An extension 110 on the inner end of the probe is received centrally through a transducer coil 112 which is retained by a locking collar 114 held by a fastening screw 116 and is adjustable by a screw 118 to relatively position it for signal generating purposes in the detection system provided and which will now be described.

The two probing members 78 and 80 are pre-set relative to a master part so that the extent to which each probe causes its terminal extension 110 to penetrate the transducer coils 112 is the same and the coils are operatively inter-connected to generate a relative displacement signal when the probes are not in equally balanced positions. Thus the probes serve as a means of detecting a difference in their relative positions which indicates axial distortion in the work part and, by electrical means which differentiates between the two probes, the relative side of the distortion with respect to the true axis of the part is also determined.

Except for situations Where the axial distortion is located on the center line between the two probes 104, the upper detection probes are able to sense "both the existence and direction of production work piece distortion and by suitable electrical connections with reversible drive motors 54, of the head and tail stock engaging devices, are able to cause the work part to be rotated through the shortest distance required to centralize the plane of axial distortion bowed upwardly as required for straightening in which position the upper probes will balance.

The third probing system 12 is disposed directly under the work piece, as best shown in FIGS. 6 and 7, and includes probe 122 biased by a spring 124 and collar 126 to project through a guide bushing 128 in a mounting 

